'Reading' the equine hoof
If, according to an old English proverb, the eyes are the windows to the soul, then for horses and humans the nails and hooves may well be the windows to inner health or medical problems.
Careful and close attention to the exterior hoof capsule and related anatomical structures often can provide a wealth of information concerning environmental factors, nutrition, infectious diseases, toxicities, deficiencies and farrier care.
In their 1999 Manual of Equine Dermatology, Dr. R.Pascoe and D. Knottenbelt address this in the section on hoof problems. "Inevitably some disorders of the hoof have profound implications for the welfare and health of the animal itself," the doctors write.
"The hoof offers (the clinician) clues that are not present elsewhere," he says, "yet the rigid hoof capsule inhibits basic palpation of the structures within the foot." And the usually pigmented surface does not allow veterinarians access to as much information as can be obtained from human nails. "Therefore," Parks advises, "it is important to develop an ability to 'read' the hoof capsule (which seems to be a life-long process)."
Clinicians should have a good understanding of the structure and function of the hoof capsule and use abnormalities in growth and appearance to gain possible insight into systemic conditions and diseases. The hoof is simply too good a "window" not to utilize the view.
Composition and pigment
The hoof is a modified cornified epithelium, and is approximately 25 percent water. It is composed of three layers.
The third, or inner, layer is the laminar layer that forms the epidermal connection to the dermal laminae below. Blood is supplied to these various layers by corresponding layers of modified vascular tissue. The periopic corium, coronary corium and laminar corium provide nutrition and vascular support to the hoof wall.
The generally accepted rate of hoof growth is 1 cm monthly for a healthy horse in a moderate environment receiving good nutrition. Deviations or extremes in numerous factors can seriously affect hoof growth and its ability to heal and regenerate.